Is it permissible to deposit money in Islamic banks, such as Faisal Islamic Bank and Abu Dhabi Islamic Bank, to avoid the amount being subject to zakat, and are the dealings of these banks truly Islamic, and can bank dealings be non-usurious if they are subject to the Central Bank?

We cannot pass judgment on the mentioned banks because a ruling depends on reviewing their transactions. What an individual should do is to ask the scholars in their country who are familiar with the transactions of these banks, or inquire about a specific transaction after describing it. The mere interaction of Islamic banks with the central bank does not make them usurious if their dealings are within the permissible limits or due to necessity that cannot be avoided.